Printing-plate and process of making same.



PATENTED MAY 17, 1904.

A SGHEGKNER. PRINTING PLATE AND PROCESS OF MAKING SAME.

APPLICATION FILED FEB. 8. 1902.

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UNITED STATES Patented May 17, 1904.

PATENT OFFICE.

ALBERT SOHEOKNER, OF ST. LOUlS, MISSOURT, ASSIGNOR OF ONE-HALF TO WILLIAM F. CARE, OF ST. LOUIS, MISSOURI.

PRINTING-PLATE AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent N 0. 760,257, dated May 17, 1904,

Application filed February 6, 1902. Serial No. 92.877- (Specimens) To rtZZ 1.071.077] it may concern:

Be it known that I, ALBERT SoHnoKNna, a citizen of the United States, and a resident of the city of St. Louis, State of Missouri, have 5 invented a new and useful Printing-Plate and Process of Making Same, of which the following is a specification.

M y invention relates to photomechanical printingplates, and has for its principal ob- 1 jects to produce a printing-plate directly from the original negative, to etch theplate deeper than is practicable with the process now commonly used, to produce a stipple and a grain with a single printing-plate, and to adapt the I plate to color-photography.

My invention consists in the plate and in the process of producing the same hereinafter described and claimed In the accompanying drawings, which form part of this specification, and wherein like symbols refer to like parts wherever they occur, Figure 1 is a diagrammatic cross-sectional view illustrating the appearance of a printingplate after the first etching. Fig. 2 is a similar view of the plate after the second etching. Fig. 3 is a magnified view of a portion of the face of a printing-plate produced by my process, the left-hand portion being unfinished. Figs. 4, 5, and 6 are detail views representing 3 the arrangement of the stipple for three-color work.

The metallic plate to be etched is cleaned and planished in the usual manner and is then coated with an emulsion or solution of substantially the following formula: Nelsons photographic gelatin, four hundred grains;

lampblack, twenty grains; bichromate of potassium, one hundred and twenty grains; chlorid of zinc, twenty grains; oxalic acid, five 4 grains; water, fifteen ounces. This solution forms a light-sensitive film which is soluble in hot water, but is rendered insoluble by the action of light. Upon saidfilm a print is made in any ordinary printing-frame. The negative used for such printing is a reversed negative made through a prism or witha reversingmirror. After the plate is printed it is laid in a tray of hot water and developed by rubbing over the surface thereof with a tuft of powder is then treated to asuitable etchingbath, such as a weak solution ofperchlorid of iron. During the etching the asphaltum partially protects the plate, and thereby produces 6 5 the grain effect, while the lampblack renders the progress of the etching more easily visible.

The plate thus etched with a grained image is I n C o hereinafter referred to as a rain-etched I I b l plate. After the etching has proceeded Tar 7 enough to pull a print therefrom, but not as faras is commonly used in etching {)llOllOlIlGChELlb iical printing-plates, the plate is washed with water to stop the" etching process, and then the film is stripped therefrom and the plate thoroughly cleaned. The plate is again coated with a thin film of some light-sensitive emul sion or solution suitable for photo-etching, such as the solution known as the enamel solution. The usual formula for this enamel 30 solution consists of eight ounces of glue (preferably Le Pages photo-engravers) to sixteen ounces of water, eight ounces of albumen to forty ounces of water, and seven hund-redand twenty grains of bichroniate of ammonia to 5 fourteen ounces of water. The grain-etched platelthus sensitized forthe second time is againprinted in the printing-frame under a glass negative made specially for this purpose. This negative does not bear any image; but 9 its surface is substantially uniform throughout, the clear-glass dots being regularly ar ranged and being of practically uniform size. This negative is formed by the action of light passing through an ordinary half-tone screen placed a short distance in frontof the sensitive glass plate, whereby the film ofthe negative becomes opaque with clcar-glass dot-s.

The second sensitive film of themetallic printing-plate thus exposed under the stippled neg ative is itself thus stippled and is then developed and fixed. Greasy ink is then carefully applied to the surface of the plate with an ink-roller, and then the plate is covered with powdered asphaltum. The superfluous powder is carefully brushed off with a camelshair brush, and the plate is then heated. By this process the powdered asphaltum adheres to the inked surface and constitutes a resist therefor; but the asphaltum powder is entirely brushed out of the uninked surfaces, which are therefore unprotected. The plate thus inked and powdered is then exposed 'to the etching-bath and etched a'second time. During this second etching the greasy ink, with the asphaltum thereon, protects the image and grain not affected by the first bath, and the stipple dots cooperate with such powder to form a supplemental resist. The balance of the plate is exposed to the etching solution.

In the process of etching the solution first attacks the portions which print the high lights out the detail and produce a proper printingdepth. By printing a stipple over the grained image and then inking the dissolving action of the solution is reduced to a minimum under the stipple dots,'and the original grain formed by the first etching is to a large extent preserved, even in the high lights. Where the etching solution cuts into the grain,- it tends to break it up into the more regular arrange"- mentof the stipple dots, and thereby gives a softer tone to the picture. As the parts affected by the second etching-bath are in the portions originally etched by the first bath,

the second etching merely increases the depth of the first etching.

The principal advantage of this process is that the etching is carried deeper and brings out more detail than is practicable in a single step and that it does so directly from the original negative and that it does-not matedirectly from the originalnegatives, as here, inbefore described. a In making such plates,

however, the arrangement of the dots is different for each plate. The dots on a plate forming the stipple are arranged in lines or rows By first graining the plate and then at right angles to each other. The several corresponding lines or rows of dots on the different plates are, however, arranged at an angle of thirty degrees relative to one another. For instance, supposing one row of dots on the yellow plate to be taken as the reference-line the corresponding row of dots on the blue plate will be at an angle of thirty degrees thereto on one side of said line, and the corresponding row of dots on the red plate will be at an angle of thirty degrees on the other side of said line. The purpose of this arrangement is to prevent the dots being superposed one on the other, and thereby prevent their intended color effect. The graining also contributes directly to this result.

My process is capable of being carried into effect by divers of the usual light-sensitive solutions, and I do not wish-to restrict myself to the formula hereinbefore set forth. I have found this formula best adapted to the process; but the quantity of gelatin therein may vary without materially affecting its efficiency. So, too, the lampblack is employed as a pigment to render the image visible during development, and it may be used in other proportions, or other pigments may be substituted therefor.

What I claim is- 1. The improvement in the process of making photomechanical printing-plates which consists in slightly etching the image into the plate with a grain, protecting the grained image, and then etching a stipple into said plate, substantially as described.

2. The process of making photom echanical printing-plates, which-consists in photographically forming the imageon said plate, then graining and slightly etching the plate, then photographically forming a stipple on said plate with a suitable resist, then protecting the grained image andagain etching, substantially as described.- r

3. The improvement in the process of maki ing printing-plates which consists in graining the plate after the image is fixed thereon and then etching the same, and afterward etching. a stipple therein while the portion not etched by the first etching is protected, substantially as described.

4:. The improvement in the process of making printing-plates, which consists in coating with a light-sensitive film a printing-plate which has been partially etched to print a grain, then printing a stipple thereon, and then etching the stipple into the plate while protecting the unetched'surface thereof, substantially as described.

5. The process of making printing-plates, which consists in photographically printing thereon'an image adapted to form an etching resist, graining and etching said plate, then coating said plate with a light-sensitive film and photographically printing a stipple thereon, then covering the unetched portions with an ink resist and again etching said plate, substantially as described.

6. The process of making printing-plates, Which consists in covering the plate With a light-sensitive film adapted to form a resist to the etching-bath, printing and fixing the image thereon, graining said plate and etching the same, covering said plate with a sec- 0nd sensitive solution and photographically printing a stipple thereon, and then inking said plate with an ink resist and etching said plate a second time, substantially as described.

7. A photomechanical relief-printing plate, etched to form the image on the printing-surface with both a grain and a stipple, substantially as described.

8. The photomechanical relief printing plate which consists of a grain-etched plate etched to print a stipple, substantially as described.

9. The process of making printing-plates, which consists in covering the plate With a film consisting of gelatin, bichromate of potassium, chlorid of zinc, a pigment and water, then printing and fixing the image thereon, and then graining and slightly etching the plate, then photographically forming a stipple on said plate with a suitable resist, then protecting the grained image and again etching, substantially as described.

10. The process of making printing-plates which consists in covering the. plate with a film consisting of gelatin, bichromate of potassium, chlorid of zinc, oxalic acid, a pigment and water, then printing and fixing the image thereon, and then graining and slightlyetching the plate, then photographically forming a stipple on said plate with a suitable resist, then protecting the grained image and again etching, substantially as described.

11. The process of making printing-plates, which consists in covering the plate with a film consisting of gelatin, lampblack, oxalic acid, bichromate of potassium, chlorid of zinc and water, then printing and fixing the image ALBERT SGHEQKNER. In presence of ZOLA TUCKER, WM. P. CARR. 

